Magnetic coupling pump

ABSTRACT

A magnetic coupling pump according to the present invention has a housing including a pump chamber a motor chamber. The rotor includes a plurality of impellers projected from top face of a substantially disc-shaped main body of the rotor to be located in the pump chamber, and a substantially cylindrical magnet section projected from back face of the main body to be located in the motor chamber. The rotor is located in engine coolant, and is driven by a stator located inward of the magnet section in the motor chamber for sucking coolant from an inlet port and exhausting it from an outlet port. The pump is provided along an inner circumference of the stator with a cavity communicating with passages of fluid along an inner circumference of the magnet section and the back face of the main body of the magnet section. The cavity admits the coolant. The pump according to the present invention is able to prevent heat-up in the inner circumferential part of the stator.

[0001] The present application claims priority from Japanese PatentApplication No. 2003-142389 of Hatano, filed on May 20, 2003, theentirety of which is hereby incorporated into the present application byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a magnetic coupling pump forpumping fluids such as engine coolant for vehicles, and moreparticularly, relates to an outer-rotor type magnetic coupling pump inwhich a stator is located toward a rotation center of a rotor havingimpellers for feeding fluids, and a substantially cylindrical magnetsection of the rotor is located around the stator.

[0004] 2. Description of the Related Art

[0005] In conventional outer-rotor type magnetic coupling pumps forengine coolant for vehicles, a rotor having impellers for feedingcoolant is located in a housing, as disclosed in Japanese Laid OpenPatent Application No. JP10-311290.

[0006] In this magnetic coupling pump, the housing includes a pumpchamber having inlet port and outlet port of coolant, and a motorchamber. The rotor includes impellers which are projected from top faceof a disc-shaped body of the rotor to be located in the pump chamber,and a substantially cylindrical magnet section which is projected fromback face of the rotor body to be located in the motor chamber. Thisrotor is located in the coolant, and is driven to rotate by rotatingmagnetic field generated by a stator located inward of the magnetsection in the motor chamber to suck the coolant from the inlet port andexhaust it from the outlet port.

[0007] In the conventional outer-rotor type magnetic coupling pump,however, there is no means of cooling down a part inward of the statorthough the outer circumference of the stator can be cooled down bycoolant interposed between the stator and the magnet section.Accordingly, heat-up of the stator and burnout of coils of the statorcaused by the former has been a concern in a high-load driving conditionusing a lot of electricity.

SUMMARY OF THE INVENTION

[0008] The present invention contemplates to solve the above mentionedproblem, and therefore, has an object to provide a magnetic couplingpump capable of preventing heat-up of an inner circumferential part ofthe stator.

[0009] A magnetic coupling pump according to the present invention is tosuck fluid from an inlet port and exhaust the fluid from an outlet port,and includes a housing and a rotor. The housing includes a pump chamberhaving the inlet and outlet ports of fluid and a motor chamber. Therotor includes: a plurality of impellers projected from top face of asubstantially disc-shaped main body of the rotor to be located in thepump chamber; and a magnet section projected from back face of the mainbody to be located in the motor chamber and having a substantiallycylindrical shape. The rotor is located in the fluid and driven by arotating magnetic field generated by a stator located inward of themagnet section in the motor chamber. A cavity is located along an innercircumference of the stator so as to communicate with passages of fluidalong an inner circumference of the magnet section and the back face ofthe main body of the magnet section.

[0010] In the magnetic coupling pump according to the present invention,fluid flows into the cavity located inward of the stator from fluidpassages along the inner circumference of the magnet section and theback face of the main body of the rotor, and the inner circumferentialpart of the stator is cooled down by this fluid.

[0011] Therefore, the magnetic coupling pump of the present invention isable to prevent heat -up of the inner circumferential part of the statorand burnout of coils of the stator, whereby becomes durable even underhigh-load driving which consumes a lot of electricity.

[0012] If the main body of the rotor is provided in the vicinity of aninner circumferential part of the stator with a plurality of throughholes, the fluid in the cavity is able to flow into the pump chamber viathe through holes of the rotor main body. That is, the fluid forms acooling stream for cooling the stator that flows from the outercircumferential side to the inner circumferential side of the stator,and further flows from the inner circumferential side of the stator tothe pump chamber. Therefore, heat-up of the inner circumferential partof the stator is further prevented, and in addition, heat-up of theouter circumferential side of the stator is properly prevented, too.Consequently, burnout of the coils of the stator and heat deformation ofthe housing are properly prevented, which further elongates a life spanof the pump even under high-load driving which consumes a lot ofelectricity.

[0013] When the rotor includes a shaft section projecting into thecavity, the shaft section is desirably provided in its outercircumference with a plurality of impellers for stirring the fluid. Withthis arrangement, the impellers are able to stir the fluid in the cavitywhen the rotor is driving, and therefore, entire area of the inner partof the stator is cooled down quickly and properly.

[0014] When the rotor includes a shaft section projecting into thecavity, moreover, it will also be appreciated that the shaft sectioninternally includes a passage with apertures opening in the cavity andin a top face side of the main body, such that the fluid in the cavitycirculates to the top face side of the main body through the passage.With this arrangement, the fluid in the cavity is able to flows outtoward the top face side of the rotor main body or into the pump chambervia the passage of the shaft section. Especially, the fluid in a bottompart of the cavity is also able to circulate to the pump chamber via thepassage. Therefore, cooling-down effect of the inner circumferentialpart of the stator is enhanced.

[0015] Furthermore, if the rotor is rotatably supported at two positionsof a position proximate to the main body and at a position in thecavity, the rotation of the rotor is stabilized, which reduces the lossof rotation moment of the rotor.

BRIEF DESCRIPTION OF DRAWINGS

[0016]FIG. 1 is a vertical section of an embodiment of the magneticcoupling pump according to the present invention;

[0017]FIG. 2 is a vertical section of the rotor of the pump of FIG. 1;

[0018]FIG. 3 is a transverse section of the rotor of FIG. 2 taken alongline III-III of FIG. 2; and

[0019]FIG. 4 is a vertical section of another embodiment of the magneticcoupling pump according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Preferred embodiments of the present invention are now describedbelow with reference to the accompanying drawings. However, theinvention is not limited to the embodiments disclosed herein. Allmodifications within the appended claims and equivalents relativethereto are intended to be encompassed in the scope of the claims.

[0021] FIGS. 1 to 3 illustrate an embodiment P1 of the magnetic couplingpump according to the present invention for feeding engine coolant W forvehicles. The pump P1 includes a housing 1 which is made from syntheticresin and has therein a rotor 15 with a plurality of impellers 17 forfeeding the coolant W.

[0022] The housing 1 includes a pump chamber 2 in which the impellers 17of the rotor 15 are located, and a motor chamber 6 located below thepump chamber 2. The pump chamber 2 has a ceiling wall 2 a and has asubstantially cylindrical shape. An inlet pipe 3 for introducing thecoolant W projects upward from the ceiling wall 2 a, and an outlet pipe4 for exhausting the coolant W projects outwardly from a circumferentialwall 2 b.

[0023] The motor chamber 6 includes a circumferential wall 7 having asubstantially cylindrical shape, a bottom wall 8 extending from a lowerinner part of the circumferential wall 7, and a stator section 9protruding upward from the bottom wall 8.

[0024] The stator section 9 is provided along its inner circumferencewith a cavity 11 to which the coolant W is admissible, and has asubstantially cylindrical shape as a whole. The stator section 9includes therein a stator 10 wound by coils 10 a for generating arotating magnetic field when electrified. A member designated by areference numeral 12 is a circuit board for rotating the rotor 15 onwhich power transistors for driving the stator 10, and a Hall elementfor detecting rotation angle of the stator 10, and so on are located. Amember designated by a reference numeral 13 is a terminal for supplyingelectricity to the circuit board 12.

[0025] The rotor 15 includes a main body 16 having a substantially discshape and a magnet section 18. The main body 16 has impellers 17projected upward from its top face 16 a. The magnet section 18 has asubstantially cylindrical shape, and extends downward from the vicinityof the outer edge of the main body 16, or from a back face 16 a of themain body 16 to be located between an outer circumference of the stator10 and an inner circumference of the circumferential wall 7. The magnetsection 18 is driven and rotates by the rotating magnetic fieldgenerated by the stator 10. In the foregoing embodiment, the magnetsection 18 is made from a material made by mixing magnetic powder intosynthetic resin material such as polyamide that forms the rotor 15except later-described shaft 20 and bearings 25.

[0026] The main body 16 is provided near the inner circumference of thestator 10 with a plurality of through holes 16 c through from the top tothe back. Located vertically in the center of the main body 16 is ashaft section 19, which includes a shaft 20 and a sliding boss section26. The shaft 20 is made of metal pipe, and penetrates the base 16. Alower end 20 b of the shaft 20 is fixed to the center of the bottom wall8 of the motor chamber 6 in the housing 1. This pipe-shaped shaft 20 isopen at its upper end, and is provided in a part submerged in thecoolant W near the lower end 20 b, or in a part near a bottom 11 a ofthe cavity 11 with a plurality of holes 22 communicating in and outsidesof the shaft 20. These holes 22 serve as inlet ports for inletting thecoolant W such that the coolant W flows through an inner passage 21 ofthe shaft 20 and flows out of the upper end of the shaft 20 serving asan outlet port 23.

[0027] The sliding boss section 26 has a cylindrical shape, and isintegrally formed with the main body 16 in the center of the main body16. Bearings 25 are fixed to upper and lower parts of an innercircumference of the sliding boss section 26 such that the shaft 20rotatably supports the sliding boss section 26. The bearings 25 are madeof resin or metal capable of reducing friction force. An E-ring 24 islocated proximate to the top end 20 a of the shaft 20 to prevent thesliding boss section 26 from coming off from the shaft 20.

[0028] The E-ring 24 is required since the rotor 15 is prone to float upwhen rotating because of negative pressure generated near the inlet pipe3. When the pump P1 is in service, the rotor 15 rotates at 3000 to 3800rpm.

[0029] The rotor 15 is submerged in the coolant W except the lower end20 b of the shaft 20 fixed to the housing 1. The sliding boss section26, which is located in the cavity 11 or inward of the stator section 9,is provided on the outer circumference in its lower part with aplurality of stirring impellers 27 for stirring the coolant W in thecavity 11.

[0030] In the magnetic coupling pump P1, the coolant W flows into thecavity 11 positioned inward of the stator 10 from fluid passages alongthe inner circumference 18 a of the magnet section 18 and the back face16 b of the main body 16 of the rotor 15, whereby the inner side of thestator 10 is cooled down.

[0031] Therefore, the magnetic coupling pump P1 is able to preventheat-up of an inner circumferential part of the stator 10 and burnout ofthe coils 10 a of the stator 10, where by becomes durable even underhigh-load driving which consumes a lot of electricity.

[0032] In the preferred embodiment, the through holes 16 c piercedthrough vertically are located near the inner circumference of thestator 10 of the main body 16. When the rotor 15 is driven and rotates,negative pressure occurs toward the inlet pipe 3, and the coolant W inthe cavity 11 flows toward the pump chamber 2 via the through holes 16 cof the main body 16. In other words, the coolant W forms a coolingstream F0 for the stator 10 that flows from the outer circumferentialside to the inner circumferential side of the stator 10, and furtherflows from the inner circumferential side of the stator 10 to the pumpchamber 2. Therefore, heat-up of the inner circumferential part of thestator 10 is further prevented, and in addition, heat-up of the outercircumferential side of the stator 10 is properly prevented.Consequently, burnout of the coils 10 a of the stator 10 and heatdeformation of the stator section 9 in the housing 1 are properlyprevented, which further elongates a life span of the pump P1 even underhigh-load driving which consumes a lot of electricity.

[0033] In the preferred embodiment, moreover, the rotor 15 includes theshaft section 19 projecting into the cavity 11, and the sliding bosssection 26 of the shaft section 19 is provided on its outercircumference with the stirring impellers 27 for stirring the coolant W.Accordingly, the impellers 27 are able to stir the coolant W in thecavity 11 when the rotor 15 is driving, and therefore, entire area ofthe inner part of the stator 10 is cooled down quickly and properly.

[0034] Furthermore, the rotor 15 includes the shaft section 19projecting into the cavity 11, and the shaft 20 of the shaft section 19internally has the passage 21 provided with apertures open into thebottom part 11 a of the cavity 11 and in the surface 16 a of the mainbody 16 such that the coolant W in the bottom part 11 a of the cavity 11circulates to the pump chamber 2 above the rotor main body 16. When therotor 15 is driven and rotates, negative pressure occurs toward theinlet pipe 3, and the coolant W in the bottom part 11 a of the cavity 11flows into the passage 21 of the shaft 20 from the inlet ports 22, andthen flows out of the outlet port 23 or the top end 20 a of the shaft 20into the pump chamber 2 above the main body 16, via the passage 21. Thatis, the coolant W forms a cooling stream F1 for the stator 10 that flowsfrom the outer circumferential side to the inner circumferential side ofthe stator 10, and flows from a bottom part of the inner circumferentialside of the stator 10 to the pump chamber 2 via the passage 21. Thus,cooling-down effect of the inner part of the stator 10 is enhanced.

[0035] In addition, in the magnetic coupling pump P1, the rotor 15, whenrotating, is supported by two bearings 25 which are located near theupper and lower end of the rotor 15, i.e., at a position near the mainbody 16 and a position in the cavity 11. Therefore, the rotation of therotor 15 is stabilized, which reduces the loss of the rotation moment ofthe rotor 15.

[0036] Although the preferred embodiment shows the shaft section 19 ofthe rotor 15 having the sliding boss section 26 with the stirringimpellers 27, the shaft section does not necessarily have to be providedwith the impellers 27.

[0037] Although preferred embodiment shows the shaft section 19 of therotor 15 having the pipe-shaped shaft 20 which serves as the fluidpassage 21, the magnetic coupling pump may include a shaft section 19Awhich has a sliding boss section 26 with the stirring impellers 27 and ashaft 20A without the passage 21, as in a magnetic coupling pump P2shown in FIG. 4.

[0038] Although the preferred embodiment shows the main body 16 of therotor 15 with a plurality of though holes 16 c through from top tobottom, the rotor 15 may include no through holes 16 c.

What is claimed is:
 1. A magnetic coupling pump for sucking fluid froman inlet port and exhausting the fluid from an outlet port, the pumpcomprising a housing and a rotor, the housing including a pump chamberhaving the inlet and outlet ports of fluid and a motor chamber, therotor including: a plurality of impellers projected from top face of asubstantially disc-shaped main body of the rotor to be located in thepump chamber; and a magnet section projected from back face of the mainbody to be located in the motor chamber, the magnet section having asubstantially cylindrical shape, the rotor being located in the fluidand driven by a rotating magnetic field generated by a stator locatedinward of the magnet section in the motor chamber, wherein a cavity islocated along an inner circumference of the stator, the cavitycommunicating with passages of fluid along an inner circumference of themagnet section and the back face of the main body of the magnet section.2. The magnetic coupling pump according to claim 1, wherein: the mainbody of the rotor includes a plurality of through holes in the vicinityof an inner circumferential part of the stator, the through holes beingthrough from the top face to the back of the main body.
 3. The magneticcoupling pump according to claim 1, wherein: the rotor includes a shaftsection projecting into the cavity; and the shaft section is provided inthe outer circumference thereof with a plurality of impellers forstirring the fluid.
 4. The magnetic coupling pump according to claim 2,wherein: the rotor includes a shaft section projecting into the cavity;and the shaft section is provided in the outer circumference thereofwith a plurality of impellers for stirring the fluid.
 5. The magneticcoupling pump according to claim 1, wherein: the rotor includes a shaftsection projecting into the cavity; and the shaft section internallyincludes a passage with apertures opening in the cavity and in a topface of the main body, whereby the fluid in the cavity circulates to thetop face side of the main body through the passage.
 6. The magneticcoupling pump according to claim 2, wherein: the rotor includes a shaftsection projecting into the cavity; and the shaft section internallyincludes a passage with apertures opening in the cavity and in a topface of the main body, whereby the fluid in the cavity circulates to thetop face side of the main body through the passage.
 7. The magneticcoupling pump according to claim 3, wherein: the shaft sectioninternally includes a passage with apertures opening in the cavity andin a top face of the main body, whereby the fluid in the cavitycirculates to the top face side of the main body through the passage. 8.The magnetic coupling pump according to claim 1, wherein the rotor isrotatably supported at two positions of a position proximate to the mainbody and at a position in the cavity.
 9. The magnetic coupling pumpaccording to claim 2, wherein the rotor is rotatably supported at twopositions of a position proximate to the main body and at a position inthe cavity.
 10. The magnetic coupling pump according to claim 3, whereinthe rotor is rotatably supported at two positions of a positionproximate to the main body and at a position in the cavity.
 11. Themagnetic coupling pump according to claim 4, wherein the rotor isrotatably supported at two positions of a position proximate to the mainbody and at a position in the cavity.